StringBuilder类型

package day97;

public class StringBuilder1 {
	public static void main(String[]args) {
//	 StringBuilder sb=new StringBuilder();
//    System.out.println("sb="+sb);
//    System.out.println("sb.length="+sb.length());
//	
//	StringBuilder  sb1=new StringBuilder("hello");
//	System.out.println("sb1="+sb1);
//	System.out.println("sb1.length="+sb1.length());
	
	
	StringBuilder  sb2=new StringBuilder();
//	StringBuilder  sb3=sb2.append("helloWorld");
//	System.out.println("sb2"+sb2);
//	System.out.println("sb3"+sb3);
//	System.out.println(sb2==sb3);
	
	
//	sb2.append("hello");
//	sb2.append("world");
//	sb2.append("java");
//	sb2.append(100);
//	System.out.println("sb2="+sb2);
	//链式编程
	sb2.append("hello").append("world").append("java").append(100);
	System.out.println("sb2"+sb2);
	sb2.reverse();//	反转方法
	System.out.println("sb2="+sb2);
	

	
    }
}

package day97;
//**为什么要转化：Builder可以使用比较好用的append和reserve方法**
public class StringBuilder相互转换 {
public static void main(String[]args) {
//	Stringbuilder转化为String
//	StringBuilder sb=new StringBuilder();
//	sb.append("hello");
//	String s=sb.toString();
//	System.out.println(s);
	
//  String转化为StringBuilder
//	String s="hello"; 
//	StringBuilder sb=new StringBuilder(s);
//	System.out.println(sb);	
	//拼接字符串
	
	}
}

字符串反转String类

package day97;

import java.util.Scanner;

public class 字符串反转String类 {
	public static void main(String[]args) {
		
Scanner sc=new Scanner(System.in);
System.out.println("请输入一个人字符串");
 String line=sc.nextLine();
 System.out.println(myReverse(line));
   
	}
public  static String myReverse(String line) {
	StringBuilder sb=new StringBuilder(line);
	sb.reverse();
	String ss=sb.toString();
	//return ss;
	return new StringBuilder(line).reverse().toString();
}

}